In a food product containing a fat, the crystallization behavior and properties of the fat exert a significant influence on many situations including development, production, storage, and distribution of the food product. Therefore, a technique for controlling fat crystallization is one of the most important issues in fat-containing food product industries.
Particularly, a fat composition of margarine, shortening, chocolate, or hard butter to be used for confectionery production or bakery production, has a high ratio of fat content in the composition, and therefore the influence of the crystallization behavior of the fat to be used is great to cause various problems.
For example, as a method for suppressing coarsening of a crystal during storage after production, Patent Document 1 proposes a fat crystallization adjustor containing diglyceride for the purpose of preventing deterioration of physical properties caused by the coarsening of fat crystals. In addition, Patent Document 2 proposes, as a method for producing a fat composition in which particulate crystals having a diameter of 20 μm or more are not generated under a long term storage, a method for producing a fat or a fat composition that does not generate particulate crystals by generating unstable crystals through rapid cooling using a coolant of −20° C. or lower or addition of unstable crystal particles of a fat.
These are attributable to the coarsening that occurs when the fat that is not sufficiently crystallized in a production step is crystallized during storage or unstable crystals become stable crystals, and the cause is considered to be insufficient fat crystallization during the production step. Particularly, a palm oil-based fat is used as a fat raw material for a plastic fat composition such as margarine and shortening, but the crystal coarsening during storage is inevitable since the crystallization speed of the palm oil is slow, and therefore, there has been a problem that it is difficult to blend a large amount of inexpensive palm oil.
Accordingly, as a method for suppressing the generation of coarse crystals of palm oil, Patent Document 3 proposes a method for suppressing the generation of palm oil particulate crystals by adding a sorbitan saturated fatty acid ester having an esterification rate of 20% or more and less than 50%. In addition, Patent Document 4 proposes a water-in-oil emulsified fat composition containing a saturated fatty acid-linked sorbitan fatty acid ester and a medium chain fatty acid, wherein coarse crystals are not generated while containing a large amount of palm oil, and Patent Document 5 also proposes a creaming property improver containing a saturated fatty acid-linked sorbitan fatty acid ester as an active ingredient.
However, these proposals focus on the suppression of crystal coarsening during long term storage and do not solve the basic problem of fully crystallizing fat during a production step, and therefore, a solution from the viewpoint of accelerating the crystallization in a short time during a production step has not been offered yet.
Previously, since it has been necessary to add a cooling unit, to increase production steps such as increasing a degree of supercooling while extremely reducing a cooling temperature, and reducing a production flow rate, or to add complicated steps such as a tempering work and a stabilizing step (aging) after production, production efficiency has been deteriorated, and the effect has been insufficient.
Particularly, in a sheet-like plastic fat composition used as being inserted into a dough of bakery or confectionery among plastic fat compositions such as margarine and shortening, the fat crystallization acceleration effect during a production step is most required since insufficient fat crystallization during a production step makes it difficult to perform a work of forming the sheet-like shape and deteriorates elasticity and flattening properties.
Also, in recent years, the use of hardened oil having a high trans acid content has been reduced and the amount of transesterified oil used being increased, but it is difficult to stably produce plastic fat compositions such as margarine and shortening using the transesterified oil, particularly randomly transesterified oil, having a slower crystallization speed as compared to the hardened oil. Therefore, the solution has been in demand.    Patent Document 1: JP 2000-345185 A    Patent Document 2: JP 2001-72992 A    Patent Document 3: JP 2007-124948 A    Patent Document 4: JP 3434463 B    Patent Document 5: JP 2007-97419 A